Load sera, provided by the NIAID Serum Bank, onto 72-well histocompatibility typing trays in one or more lots of 2000 trays each. Trays will be prepared within ten working days of request from the Project Officer. Maintain an inventory of approximately 15,000 filled typing trays kept at -70 degrees C in a mechanical freezer(s). Once a week throughout the year, package and ship HLA typing trays to designated tissue typing laboratories as requested by requisition from NIAID, or by telephone from the Project Officer. Consult with thee Project Officer periodically and when required as problems arise.